If you want to reset all current counters this is easy. Just invoke the menu, and use reset counters option.
But what if you want to keep the distance counters intact and reset only max and average speed, lets say? Or want to set distance to some initial value (e.g. to match your car's odometer)?
It is possible, but requires few more steps. Invoke the menu again:
and tap on the "TRIPS" option:
List of trips will open, here tap on the Edit button:
Now tap on the row with the trip you want to reset only specific counters for:
You can now review the current and total trip counters and by holding your finger on a specific counter cell and releasing, you'll get to a particular counter reset options:
In case you need to set distance to some value (e.g. initial odometer value in your car), please tap on a distance cell to open options that include setting the distance.
This is it. Selective counter reset/set is hidden a little bit, but you don't need it every day hopefully!